JP2825048B2 - Semiconductor silicon substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor silicon substrate, and more particularly to a base semiconductor silicon substrate suitable for forming a thick epitaxial layer (for example, about 100 .mu.m).

[0002]

2. Description of the Related Art In a semiconductor silicon substrate (hereinafter simply referred to as a substrate), chamfers are provided on each of the front and rear peripheral edges in order to prevent chipping or cracking during handling or alignment of the substrate. I have.

FIG. 6 shows a conventional example of the substrate 1, in which chamfered portions 2 and 3 are provided on the front and back of the peripheral portion of the substrate 1, respectively. As shown in FIG. 7, the chamfered portions 2 and 3 on the front and back of the conventional substrate 1 are generally configured to be symmetrical on the front and back.

Incidentally, the size of the chamfer angle of the substrate 1 (the angle between the extended surface of the main surface of the substrate 1 and the inclined surfaces of the chamfered portions 2 and 3) is limited only from the viewpoint of preventing the substrate 1 from being chipped or cracked. However, it is determined in consideration of the viewpoint of preventing the harmful effects due to the edge crown 4 (FIG. 8) generated during the formation of the epitaxial layer.

From the standpoint of preventing chipping or cracking of the peripheral portion of the substrate 1 only, it is sufficient to increase the chamfer angles θ1 and θ2 so as to approach 45 °. Emergence and growth are promoted. When such an edge crown 4 is formed on the front side of the substrate 1, the contact with the mask pattern is deteriorated, so that the pattern cutting accuracy is reduced. On the other hand, the thickness of the epitaxial layer is, for example, 100 μm
When there is a special requirement as described above, the edge crown 4 is generated not only on the growth surface but also on the back surface.
In this case, when the substrate 1 needs to be placed on a flat surface, for example, in a photolithography process or the like after the epitaxial growth, rattling occurs because the edge crown 4 on the back surface is not at a uniform height over the entire outer periphery of the substrate. In the case of fixing by suction, the edge crown 4 disturbs and cannot be completely sucked, and furthermore, the flatness of the back surface of the substrate 1 deteriorates, and the substrate 1 is tilted, so that the pattern cut on the front surface is deteriorated. . Therefore, when chamfering a base substrate for forming a thick epitaxial layer as described above, care must be taken not to cause any adverse effects due to the edge crown on both the front and back surfaces.

Therefore, in the conventional substrate, the chamfering angle is set to, for example, about 11 ° to 22 ° in consideration of the harmful effect of the edge crown 4.

[0007]

However, the generation and growth of the edge crown 4 does not depend only on the chamfer angle but on the thickness of the epitaxial layer formed on the substrate 1.

That is, when the thickness of the epitaxial layer is small, the edge crown 4 does not occur or the edge crown 4 grows only slightly, but when the thickness is large, the edge crown 4 grows large. become.

Therefore, it is necessary to determine the chamfer angle in consideration of the thickness of the epitaxial layer to be formed.
In the case of the one-stage chamfering structure, if the chamfering angle is further reduced, the chamfering angle approaches the original shape of the substrate, and the function of preventing chipping or cracking is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a substrate capable of simultaneously preventing an adverse effect due to the occurrence of an edge crown and preventing occurrence of chipping or cracking.

[0011]

According to the present invention, there is provided a semiconductor silicon substrate in which the front and rear edges are chamfered, wherein at least one of the front and rear chamfers has a two-step chamfer structure, and the inner chamfer has a chamfered portion. A chamfer angle between an extended surface of the main surface of the substrate and an inclined surface thereof is 3 °.
In the outer chamfered portion, the chamfer angle between the extended surface of the main surface of the substrate and the inclined surface is 11 ° to 4 °.
It is 5 °.

[0012]

According to the above means, the inner chamfer angle is set to 3
Since the angle is relatively small, that is, 10 ° to 10 °, it is possible to prevent the occurrence of edge crown that occurs at the boundary between the main surface of the substrate and the inner chamfered portion.

The boundary between the inner chamfered portion and the outer chamfered portion is lower than the main surface of the substrate due to the presence of the inner chamfered portion. The height from the main growth surface can be suppressed. As a result, adverse effects due to the edge crown can be effectively prevented.

Further, in the outer chamfered portion, if the chamfer angle is selected independently of the inner chamfered portion by giving priority to the function of preventing chipping and cracking, the strength of the substrate against chipping and cracking can be reduced. Can be more enhanced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the substrate according to the present invention will be described.

FIG. 1 shows a part of a substrate 10 of the embodiment. Symmetrical chamfers 11 and 12 are formed on the front and back sides of the substrate 10 at the periphery thereof. The front chamfer 11 includes an inner chamfer 11 a and an outer chamfer 1.
1b, while the back chamfered portion 12 comprises an inner chamfered portion 12a and an outer chamfered portion 12b, and the chamfered portions 11 and 12 are symmetrical as a whole.

That is, the widths of the inner chamfers 11a and 12a and the outer chamfers 11 and 12 are different from each other.
The widths of b and 12b are equal to each other. In addition, the chamfer angle θ3 from the extension of the main surface (front surface) of the front inner chamfer 11a and the inner chamfer 1 on the back side.
Chamfer angle θ from the extension of the main surface (back surface) in 2a
4 has the same angle (3 ° to 10 °). Also,
In the front and back outer chamfers 11b and 12b, the chamfer angle θ5 from the extension of the main surface (front surface) in the front outer chamfer 11b and the extension of the main surface (back) in the back outer chamfer 12b. It is the same angle (11 ° to 45 °) as the chamfer angle θ6. As a result, the chamfered part 11 and the chamfered part 12 are symmetrical as a whole.

For example, when the thickness of the epitaxial layer is about 100 μm, the vertical distance (chamfer allowance) h1 from the main surface to the boundary between the inner chamfers 11a, 12a and the outer chamfers 11b, 12b. , H2 are set to 15 μm or more (see FIG. 2). If the thickness is 15 μm or more, the edge crown is not projected from the main surface of the epi growth, or even if it is projected, its height can be suppressed to such an extent that no adverse effect is caused by the edge crown. On the other hand, the thickness d of the peripheral portion of the substrate 10 is set to be ２ or more of the regular thickness D. If the thickness D is smaller than 2/5, the peripheral edge is likely to be chipped or cracked due to an external impact at the time of handling or sticking of the susceptor pocket to the substrate during epi deposition.

Here, the reason why the two-step chamfering structure is adopted will be described. The chamfer angles θ3 and θ4 of the inner chamfers 11a and 12a are made smaller than the chamfer angles in the conventional one-step chamfer, and While suppressing the occurrence of edge crowns at the boundary between the main surface and the inner chamfers 11a and 12a, the chamfer angles θ5 and θ6 of the outer chamfers 11b and 12b are changed to the chamfer angles (11 ° ２２22 °) or more (11 ° -45 °) to prevent chipping and cracking of the peripheral portion.

It is easily found from experience that the smaller the chamfer angles θ3 and θ4 are, the more the growth of the edge crown occurring at the boundary between the main surface of the substrate 10 and the inner chamfers 11a and 12a is suppressed. But, in particular,
If the angle is less than 8 °, in the polishing process performed after the chamfering step, sagging during polishing is added, and the main surface of the substrate 10 and the inner chamfered portions 11a and 12a are continuously connected. It has been confirmed by the test that no occurrence of odor occurs.

Although the cause is not clear, as in the case where the chamfer angles θ3 and θ4 are 10 °, the main surface of the substrate 10 and the inner chamfers 11a, 12a are polished.
Even when the boundary portion with a is not so smooth, when the two-stage chamfering structure is adopted, as shown in FIG. 3, the inner chamfered portions 11a and 12a and the outer chamfered portion 1 are formed.
It has been confirmed by a test that an edge crown 14 is generated at the boundary between the first and second substrates 1b and 12b, and the generation and growth of the edge crown at the boundary between the main surface of the substrate 10 and the inner chamfers 11a and 12a are suppressed. I have.

Specifically, a vertical (pancake-type) epi-deposition apparatus is used at a temperature of 1130 ° C. and a growth rate of 1.5 μm / mi.
In forming an epitaxial layer having a thickness of 120 μm under the condition of n, a substrate having a chamfer angle of 10 ° in one-step chamfering, an inner surface chamfering angle of 10 ° in a two-step chamfer, and a chamfer margin (h1, h2 in FIG. 2) The height of the edge crown 14 after forming the epitaxial layer was compared using a substrate having a thickness of 15 μm and an outer chamfer angle of 22 °.

In the substrate having the single-stage chamfered structure, relatively high edge crowns of 5 μm to 15 μm were generated on the front side and 15 μm to 25 μm on the rear side. The height of the edge crown is 0 μm to 5 μm on the front side and 1 μm to 6 μm on the back side.
It was confirmed that it was relatively low at μm.

Since the height of the edge crown also depends on the epi-deposition temperature and the epi-thickness, it is presumed that taking these conditions into consideration, a substrate having an inner chamfer angle of 10 ° can be sufficiently used for practical use. Therefore, in the present application, the upper limit of the inner chamfering angle is set to 10 °. On the other hand, the lower limit is 3 °
The reason is that it is difficult to create a chamfering jig of 3 ° or less with the current processing accuracy, and that even if a jig can be created, the chamfering accuracy cannot be guaranteed. Further, when this angle is reduced, the effective area of the main surface of the substrate is reduced.

The outer chamfer angles θ5 and θ6 are 11 °.
The reason why the angle is set to about 45 ° is that the substrate has a function of preventing chipping or cracking at least to the same extent as that of the conventional one-stage chamfered structure. However, in the case of the present application, the outer chamfer angles θ5 and θ6 are used without much consideration of the point of occurrence of the edge crown and from the viewpoint of preventing chipping or cracking.
It is possible to select That is, it is possible to make the outer chamfer angles θ5 and θ6 close to 45 °.
However, when the angle is set to 45 ° or more, the inner chamfers 11a and 12a and the outer chamfers 11b and 12
In some cases, the growth of the edge crown 14 occurring at the boundary with the edge b becomes remarkable.
It is necessary to make h2 large so that the tip of the edge crown does not protrude from the main surface of the epitaxial layer.

As described above, the chamfering margins h1 and h2 may be selected so that the tip of the edge crown does not protrude from the formed epitaxial layer. The values of the chamfering margins h1 and h2 are limited to the aforementioned value of 15 μm. Alternatively, depending on the case, a size smaller than 15 μm can be selected.

According to the substrate configured as described above, the following effects can be obtained.

That is, according to the substrate 10 of the above embodiment, the chamfer angle θ3 of the inner chamfer 11a on the front side is set to 3 °.
Since the angle is made as small as 10 ° to 10 °, it is possible to suppress the growth of the crown generated at the boundary between the surface of the substrate 10 and the inner chamfer 11a.

The boundary between the inner chamfered portion 11a and the outer chamfered portion 11b is located at a position lower than the surface due to the presence of the inner chamfered portion 11a. Can be suppressed. As a result, adverse effects due to the crown can be prevented.

Further, in the outer chamfered portion 11b, if the chamfering angle is selected independently of the inner chamfered portion 11a by giving priority to the function of preventing chipping and cracking, the strength of the substrate 10 against chipping and cracking can be reduced. It can be higher than before.

Although a chamfered structure with three or more steps can be used, the effect is considered to be almost the same as that of the case with a two-step chamfered structure.
We think that the two-step chamfering structure is better.

FIG. 4 shows a substrate 10 according to a second embodiment of the present invention.

The difference between the substrate 10 of the second embodiment and the substrate of the first embodiment is that the shape of the chamfered portion 12 on the back side of the substrate 10 is asymmetric with the chamfered portion 11 on the front side. Is a one-stage chamfered structure.

The chamfer angle θ7 from the extension of the main surface (front surface) of the front inner chamfer 11a is 3 ° to 3 °.
The chamfer angle θ8 from the extension of the main surface (front surface) of the outer chamfered portion 11b on the front side is 11 ° to 45 °. On the other hand, the chamfer angle θ9 on the back side is 11 ° to 4 °.
5 °.

The reason why the back chamfered portion 12 has a one-stage chamfered structure is that, for example, the substrate 1 on which an epitaxial layer is formed using a cylinder type (barrel type) epi deposition apparatus.
In this case, since the occurrence of the edge crown is observed only on the front side, the chamfered portion 12 on the back side is considered to be a conventional one-stage chamfered structure. In this case, the chamfer angle θ9 of the chamfered portion 12 is not particularly limited, but it is preferable that the angle be as close to 45 ° as possible, mainly for preventing chipping and cracking.

FIG. 5 shows a substrate 10 according to a third embodiment of the present invention.

The substrate 10 of the third embodiment is different from the substrate of the first embodiment in that the shape of the chamfered portion 12 on the back side of the substrate 10 is asymmetrical to the chamfered portion 11 on the front side. Is a one-stage chamfered structure.

The chamfer angle θ10 of the front chamfer 11 from the extension of the main surface (surface) is 11 ° to 4 °.
5 °, on the other hand, the chamfer angle θ11 from the extension of the main surface (front surface) of the inner chamfered portion 12a on the back side is 3 ° to 10 °.
°, the chamfer angle θ12 from the extension of the main surface (surface) of the outer chamfered portion 12b is 11 ° to 45 °.

Here, the reason why only the rear chamfered portion 12 has the two-stage chamfered structure is that, for example, in the case of the substrate 10 on which an epitaxial layer is formed using a vertical (pancake type) epi deposition apparatus, This is because the generated edge crown is higher on the back side, and if the front side edge crown is not so problematic, it is considered that only the back side should have a two-step chamfer structure.

In other respects, the substrate 1 of the first embodiment
It is similar to the case of 0.

Although the substrate 10 according to the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0042]

According to the substrate according to the present invention, in a semiconductor silicon substrate in which the front and rear edges are chamfered, at least one of the front and rear chamfers has a two-step chamfer structure, and the inner chamfer portion has the substrate chamfer. The chamfer angle between the extended surface of the main surface and the inclined surface is 3 ° to 10 °, and the chamfer angle between the extended surface of the main surface of the substrate and the inclined surface is 11 ° to Since the angle is 45 °, it is possible to effectively prevent the adverse effects caused by the generation of the edge crown and to prevent the occurrence of chipping or cracking.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of a substrate according to a first embodiment.

FIG. 2 is a side view showing a part of the substrate of the first embodiment.

FIG. 3 is a partial side view showing a state of occurrence of an edge crown in the substrate of the first embodiment.

FIG. 4 is a side view showing a part of the substrate of the second embodiment.

FIG. 5 is a side view showing a part of a substrate according to a third embodiment.

FIG. 6 is a side view showing a conventional substrate.

FIG. 7 is a side view showing a part of a conventional substrate.

FIG. 8 is a partial side view showing a state of occurrence of an edge crown in a conventional substrate.

[Explanation of symbols]

 10 substrate 11,12 chamfer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/304 H01L 21/02

Claims (1)

(57) [Claims] 1. A semiconductor silicon substrate having chamfered front and back edges, wherein at least one of the front and back chamfers has a two-step chamfer structure, and an inner chamfer has an extended surface of the main surface of the substrate. The chamfer angle between the inclined surface and the outer chamfered portion is 3 ° to 10 °, and the chamfered angle between the extended surface of the main surface of the substrate and the inclined surface is 11 ° to 45 °. A semiconductor silicon substrate characterized by the above-mentioned.